Cerebrovascular accidents have varied causes and consequences. Cerebrovascular accidents include, for example, strokes and head injuries, and can lead to hemorrhage, embolism, thrombosis, and complete or partial loss of function of one or both arms or legs. For example, hemiplegia, or paralysis on one side of the body is a frequent consequence of strokes. Regardless of the cause, cerebrovascular accident victims follow a similar course of rehabilitation. Immediately after the trauma, the muscle tone of the limb usually becomes hypotonic, or flaccid. During this period, there is a tendency for subluxation of the shoulder. Rehabilitation during this period attempts to maintain muscle tone and a full range of motion of the limb. After some time, the muscles may lose their inhibitory forces and become hypertonic, or spastic. This increase in spasticity causes the muscles to contract and follow certain patterns of movement called synergies. Therapy at this point consists of movement of the arm while following these synergies. Therapy of this sort is called "range of motion exercise". Attempts to follow the arm in non-synergy patterns usually results in a spasm, and may cause the patient considerable pain. Most patients stay at this stage, showing varying degrees of spasticity.
The next stage in the rehabilitation process is the breaking of synergies. As the patient loses muscle spasticity and regains voluntary muscle control, he will be able to follow patterns other than the synergies. This process will continue until the patient recovers functional use of his arm. Patient recovery can stop at any point and with varying degrees along this process. Therefore, there are two main categories of patients, with different therapeutic goals.
The flaccid patient has little or no muscle tone; therefore, his goal is to increase muscle tone. The spastic, conversely, has too much tone. In extreme spastic cases, the slightest movement may trigger the spasm, since there is nothing to inhibit muscle contraction. However, a constant stress applied to a muscle is inhibitory to muscle stimulation. The goal of the spastic patient is to decrease muscle tone by constant and slow stretching of the muscles.
In both cases, maintained or increased range of motion is an important goal. Unless range of motion is maintained, permanent shrinkage of the muscles will occur and full use of the limbs will never be regained.
Cerebral vascular victims require numerous hours of therapy during rehabilitation. Often the amount is not optimal due to the workload of the therapist and monetary constraints on either the patient, the hospital or extended care facility, or both. While machines are extensively used for improving arm strength and muscle tone in a healthy person, little attention has been paid to devices or machines for rehabilitation of an arm of a patient who has suffered cerebral vascular trauma. At least one passive range of motion appliance, that shown in U.S. Pat. No. 4,205,666, is known; however, this device requires the patient to supply the power needed to exercise the disabled arm. Only limited improvement is attainable and not all patients would be capable of using such a device. An unmet need, therefore, exists for device which will supply the most basic range of motion exercises necessary for rehabilitation, i.e. elbow extension and flexion, and wrist supination and pronation to achieve the desired rehabilitation in both flaccid and spastic patients.